⊙胃癌 GASTRIC CANCER⊙　

CD44v6基因表达与胃癌危险因素的关系

孙喜文,申宝忠,石美森,戴旭东

孙喜文,石美森,戴旭东,哈尔滨医科大学肿瘤研究所 黑龙江省哈尔滨市150040
申宝忠,哈尔滨医科大学第三临床医学院 黑龙江省哈尔滨市150040
孙喜文，男，1955-05-01生，黑龙江省嫩江县人，汉族.1978年毕业于哈尔滨医科大学，1994年哈尔滨医科大学硕士研究生毕业，
研究员.主要从事消化系统和呼吸系统恶性肿瘤病因学研究.
项目负责人 孙喜文,150040,哈尔滨医科大学肿瘤研究所 黑龙江省哈尔滨市南岗区哈平路150号. sxw@hljzls.com.cn
电话:0451-6623342 传真:0451-6665003
收稿日期 2002-06-22 接收日期 2002-07-09

Relationship between CD44v6 expression and risk factors in
 gastric carcinoma patients.

Xi-Wen Sun,Bao-Zhong Shen, Mei-Sen Shi, Xu-Dong Dai

Xi-Wen Sun,Mei-Sen Shi, Xu-Dong Dai, Cancer Research Institute, Harbin Medical University, Harbin 150040, Heilongjiang
Province, China
Bao-Zhong Shen, The Third Clinic Medical College, Harbin Medical University, Harbin 150040, Heilongjiang Province,
China
Correspondence to: Dr Xi-wen Sun, Cancer Research Institute, Harbin Medical University, 150 Harping Road , Harbin
150040, Heilongjiang Province, China. sxw@hljzls.com
Received 2002-06-22 Accepted 2002-07-09

Abstract
AIM:To study relationship between expression of CD44v6 and some risk factors to which gastric cancer (GC) patients
 exposed.

METHODS:The case-case control study was conducted to investigate the risk factors exposure and the tissue samples were collected. The expression of CD44v6 was detected by S-P immunohistochemical technique.

RESULTS: The positive rate of CD44v6 was 62% in the 150 gastric cancer cases. There were significant associations between expression of CD44v6 and depth of invasion, UICC TNM classification, and lymph node metastasis of gastric cancer (P <0.01). The positive rate was observably higher in the psychic depression for long-term and gastric ulcer exposure group than that in the non-exposure group. In patients with more consumption of beans, shallot and garlic, the rate was lower than that with lower consumption (P <0.001). The positive rate of CD44v6 was higher in exposure to depression model and gastric ulcer than that in control. The lower positive rate of CD44v6 was observed in the group of more soy and soy products consumption(≥3 times/wk vs. none, P <0.001) and in the group with frequent shallot and garlic consumption (≥7times/wk vs. none, P <0.001). In the lymph node metastasis of gastric cancer group, the positive rate was higher for exposure frequently to salinized food (≥7 times/wk vs none), taking meals at irregular times, history of atrophic gastritis and psychic depression (P <0.05).

CONCLUSIONS: The expression of CD44v6 is correlated with progression, metastasis of GC and UICC TNM classification, as well as with some risk factors to which GC patients exposed.

Sun XW, Shen BZ, Shi MS, Dai XD. Relationship between CD44v6 expression and risk factors in gastric carcinoma patients. Shijie Huaren Xiaohua zazhi 2002;10(10):1129-1132


摘要
目的:探索CD44v6拼接变异体（CD44 splice variants,CD44v）的阳性表达与胃癌危险因素的关系.

方法:采用病例-病例对照研究方法对胃癌患者进行危险因素暴露调查并采集组织标本，对组织标本经SP免疫组化染色法进行分析.

结果:在150例胃癌组织标本中,CD44v表达阳性率为62 %.CD44v6阳性表达率的高低与胃癌的浸润深度、TNM分期、淋巴结转移有显著关系（P <0.01）. 暴露于精神长期处于压抑状态、胃溃疡等因素CD44v6阳性表达率明显高于非暴露者；经常吃大豆及大豆制品（≥3次/wk vs 不吃, P <0.001） 、经常食用葱蒜类食品CD44v6阳性表达率明显低于不食用者（≥7次/wk vs 不吃,P <0.001）.在有淋巴结转移的胃癌患者中暴露于三餐不按时、经常吃腌晒盐渍食品(≥7次/wk vs 不吃)、慢性萎缩性胃炎和精神长期处于压抑状态等因素CD44v6阳性表达率明显高于非暴露者（P <0.05）.

结论:CD44v6阳性表达率的高低与胃癌的浸润深度、TNM分期、淋巴结转移有显著关系，与暴露于不良饮食习惯、胃慢性疾病及精神神经因素关系密切，多食用大豆及其制品、经常食用葱蒜类食品具有降低胃癌发病的作用.

孙喜文，申宝忠，石美森，戴旭东. CD44v6基因表达与胃癌危险因素的关系.世界华人消化杂志 2002;10(10):1129-1132


0 引言
胃癌是严重危害人类健康的常见恶性肿瘤之一^[1-4] .其病因学研究已有许多报道，多数学者认为胃癌的发生、发展与食物营养、幽门螺杆菌感染、饮食习惯、饮用水源污染等因素有着显著的关系和生物效应，精神心理、家族遗传等因素也被认为是胃癌发病的重要因子^[5-21] .胃癌的发生发展与多种癌基因有关.CD44v6是黏附分子家族成员之一，他是一种存在于细胞表面的跨膜糖蛋白，能介导淋巴细胞归巢并参与细胞-细胞间黏附，在肿瘤的发生、发展和转移中起重要作用^[22-26] .本文就CD44v6蛋白表达与胃癌危险因素暴露之间的关系进行分析.

1 材料和方法
1.1 材料 胃癌150例来自黑龙江省肿瘤医院腹外科手术且经病理确诊的病例，术前未接受过放疗和化疗者.全部标本均经甲醛固定，石蜡包埋，作厚4 mm切片.CD44v6鼠抗人单克隆抗体（工作效价为1:50）及S-P试剂盒均购自北京中山生物制品有限公司.
1.2 方法 采用常规SP免疫组化染色法.
   统计学处理 实验结果的统计分析采用c2检验及四格表确切概率法；暴露因素与CD44v6阳性表达的关系采用SAS6.12软件包非条件Logistic回归计算比值比和95 %可信限.

2 结果
胃癌150例原发灶中CD44v6呈阳性者为93例，阳性率为62.8%.临床分期与CD44v6阳性表率关系密切,Ⅲ-Ⅳ期阳性表达率（82.9 %）显著高于Ⅰ-Ⅱ期（43.8 %）.病变浸润深度与CD44v6阳性率有关，侵及浆膜层(78.0 %)显著高于未侵及浆膜层（37.3%）（P <0.01）.在有淋巴结转移的病例中，CD44v6表达阳性率（81.6 %）显著高于无淋巴结转移者（25.0 %）.在CD44v6表达阳性的93例胃癌组之中，有淋巴结转移者占86.0 %（表1）.

表1 CD44v6表达与胃癌病理学特征的关系    
   经性别、年龄因素调整后进行单因素非条件Logistic回归分析，结果显示，在调查的58个暴露因素中，有精神长期处于压抑状态等18个因素与CD44v6阳性表达有统计学显著意义（表2）.

表2 CD44v6表达与胃癌危险因素暴露的关系

   将单因素分析所得18个具有统计学显著意义的变量，纳入多元Logistic回归模型，采用似然比检验，进行模型拟合，结果表明：三餐不按时(≥3次/wk)、经常吃腌晒盐渍食品、慢性萎缩性胃炎、胃溃疡、精神长期处于压抑状态均和CD44v6阳性表达有密切关系，增加了胃癌发生的危险（表3）.

表3 CD44v6与胃癌暴露因素的多因素条件回归分析

3 讨论
近十几年来，胃癌发病在许多发达国家虽然呈下降趋势，但由于人口老龄化，每年新病例的绝对数字却一直在增加.国内外在该病病因学研究上虽然有一些进展，但对其危险因素方面的报道不一.为进一步明确和验证其病因，本课题在哈尔滨市1995-1999年201例原发性胃癌患者病例对照研究的基础上，结合SP免疫组化染色技术观察CD44v6在150例原发性胃癌组织中的表达情况，从分子水平探讨其与众多胃癌危险因素的关系.
  CD44是一种分布极为广泛的细胞表面跨膜糖蛋白，属于表面黏附因子，主要参与细胞与细胞、细胞与基质之间特异性的粘连过程，其拼接变异体主要表达在上皮源型细胞和肿瘤组织中^[27-30].国内外文献报道CD44v6分子在人类胃癌组织中的阳性表达率为
64-77 %，其阳性表达与胃癌的进展程度有关^[22-38] .本结果显示，胃癌原发灶CD44v6阳性表达率为62 %.通过比较TNM分期CD44V6染色强度发现，Ⅲ-Ⅳ期胃癌CD44v6阳性表达率显著高于Ⅰ-Ⅱ期（P <0.01），癌组织侵及浆膜层者的CD44v6阳性率明显高于未侵及浆膜层者（P<0.01）.这说明CD44v6表达强度与胃癌的浸润深度及病期进展有关，其阳性预示胃癌具有更强的侵袭、转移能力，容易向周围组织扩散.本研究显示CD44v6阳性率在淋巴结转移组明显高于淋巴结未转移组（P <0.01)，说明CD44v6表达与胃癌的淋巴结转移密切相关,与李泽民et al ^[39]的研究结果一致.胃癌细胞在异常分化中获得CD44v6的表达，也像淋巴细胞归巢一样向淋巴结转移，模拟循环淋巴细胞的行为.由此得出结论，CD44v6阳性的胃癌患者将需要更彻底的淋巴结清扫.
  胃癌的病因以环境因素为主，尤以饮食最为重要.胃癌的发生与饮食的种类、饮食习惯、烹调方式等有关^[5,6,12,14] .食用腌晒、盐渍食品与胃癌发生呈正相关，并有随食用腌晒盐渍食品总量的增加其危险性明显增加的趋势 ^[16] .张沥et al  ^[40]用热盐水成功建立了胃癌前病变萎缩性胃炎的动物模型，说明盐及其盐渍食品是胃癌的致病因素.我们的研究结果显示经常吃腌晒盐渍食品与CD44v6阳性表达存在显著性正关联，并具有增加淋巴结转移的危险性.有研究表明，在肉、鱼的腌晒过程中蛋白质分解生成氨基酸，其中脯氨酸、精氨酸脱羧极易形成腙胺，在合适条件下与亚硝基化剂生成N-亚硝基化合物，其具有强致癌性，可使许多动物产生肿瘤.盐渍食品除高盐能反复破坏胃黏膜屏障外，主要还是硝酸盐和亚硝酸盐过高，为生成N-亚硝基化合物提供前体.经常吃烟熏腊味食品与CD44v6阳性表达呈正相关.动物肉类在熏制和炙烤过程中，高温加热形成多环芳烃类物质，其中被公认的强致癌物有3，4-苯并芘.这提示我们不良饮食习惯是哈尔滨市胃癌高发的重要病因之一.
   以往流行病学研究分析结果提示，经常食用大豆及其制品、奶及其制品、葱蒜类食品有降低胃癌危险性的趋势^[10,13] .本研究结果显示，经常食用豆制品、奶制品、新鲜蔬菜（≥25 Kg/a）与CD44v6表达呈负关联，对胃癌有预防作用.目前已有实验室证据证实豆类中含有多种蛋白酶抑制剂、不饱和脂肪酸和酚类化合物，对致癌过程和亚硝胺的形成有抑制作用；奶类中富含钙和维生素A，还有蛋白质的胶体，对胃黏膜有保护使其免受毒物的侵害；新鲜蔬菜及水果中富含维生素C和A，维生素C能阻止胃内亚硝胺致癌物的形成，维生素A有提高胃黏膜上皮抗癌作用^[41-43] .大蒜提取物中的双丙烯基硫化物和丙烯基甲基三硫化物使胃的泌酸功能增强，使胃内亚硝酸盐的含量及霉菌、细菌的检出率明显下降 .吸烟能影响胃黏膜微循环、影响机体免疫功能，可使胃黏膜内前列腺素合成减少，还可以降低幽门括约肌张力，吸烟和饮酒只微弱地使胃癌危险性增加 ^{[9，16，20，21，44-47]} .本研究结果表明CD44v6阳性表达与吸烟、饮酒在单因素分析中均呈正相关，但未能进入多因素比例风险模型，表明他们不是胃癌独立作用的因素，可能和其他因素联合作用.吸烟可导致消化性溃疡发生，并延缓溃疡愈合.消化性溃疡是胃癌的危险因素之一，吸烟能否先导致其发生，而后继发胃癌或直接诱发胃癌，此点还有待于进一步研究.另外，Parsonnet研究得出吸烟还与萎缩性胃炎有密切关系的结论.高浓度乙醇可直接损伤上消化道黏膜上皮、增加黏膜细胞对致癌物的通透性、促使胃内产生的亚硝胺增多，长期饮酒或酗酒可诱发慢性萎缩性胃炎.
  研究表明，胃溃疡、慢性萎缩性胃炎与胃癌的发生率呈正相关，不典型增生的CD44v6阳性旅可达30%以上^[48-51] .本研究资料提示（不论单因素分析或多因素分析），慢性萎缩性胃炎和胃溃疡均与CD44v6表达显著相关，并具有增加淋巴结转移的危险性，这有力的证明了胃慢性疾病史是哈尔滨市胃癌高发的主要诱因.其作用机制可能是胃慢性病变使胃黏膜屏障发生破坏，有利于致癌剂与生发上皮接触，从而增加胃肿瘤的发生.因此重视对胃部慢性疾病和癌前病变的防治，对于降低胃癌的发病率和死亡率无疑是有重要意义的.


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